Variation of deformation mechanisms within the
progressive-retrogressive mylonitization cycle of limestones:
Brunovistulian sedimentary cover (the Variscan orogeny of the
Southeastern Bohemian Massif)

J 2001

Variation of deformation mechanisms within the progressive-retrogressive mylonitization cycle of limestones: Brunovistulian sedimentary cover (the Variscan orogeny of the Southeastern Bohemian Massif)

ŠPAČEK, Petr, Jiří KALVODA, Eva FRANCŮ and Rostislav MELICHAR

Basic information

Original name

Variation of deformation mechanisms within the progressive-retrogressive mylonitization cycle of limestones: Brunovistulian sedimentary cover (the Variscan orogeny of the Southeastern Bohemian Massif)

Authors

ŠPAČEK, Petr (203 Czech Republic, guarantor), Jiří KALVODA (203 Czech Republic), Eva FRANCŮ and Rostislav MELICHAR (203 Czech Republic)

Edition

Geologica Carpathica, Bratislava, Slovak Academic Press Ltd., 2001, 1335-0552

Other information

Language

English

Type of outcome

Článek v odborném periodiku

Field of Study

10500 1.5. Earth and related environmental sciences

Country of publisher

Slovakia

Confidentiality degree

není předmětem státního či obchodního tajemství

Impact factor

Impact factor: 0.167

RIV identification code

RIV/00216224:14310/01:00005224

Organization unit

Faculty of Science

UT WoS

000172529600001

Keywords in English

Brunovistulicum; microstructures; limestones

Abstract

V originále

This study deals with the calcite mylonites of the Brunovistulian sedimentary cover developed in frontal thrust area of Moravian nappe units. The inhomogeneous structure of sedimentary protoliths allowed the analysis of the contrasting behavior of calcite in matrix and porphyroclasts and the interpretation of microfabric evolution during deformation under low temperature conditions. Several stages of microfabric evolution characterizing progressive as well as retrogressive deformation are distinguished. Generally, the progressive phase of mylonitization is characterized by grain growth in the matrix and the grain size reduction of the porphyroclasts leading to a stress-induced equilibration of grain size. During the initial deformational stages the calcitic porphyroclasts deformed brittlely and the strain was strongly localized into the ductile matrix. With continuing evolution the onset of the dynamic recrystallization of porphyroclasts occured, which obviously preceded a significant grain growth in the matrix. With rising temperature during deformation, grain growth predominated after grain size homogenization was finished. The lack of effective dynamic recovery along the stages of the progressive low temperature phase of deformation is discussed. Core-and-mantle structures which are characteristic for initial stages of progressive deformation carry microfabric features which document the dominance of grain boundary bulging and/or nucleation recrystallization. Formation of subgrains within the porphyroclasts is only a rarely observed feature which probably could not led to significant grain size reduction. The higher effectiveness of nucleation and recrystallization via migration of grain boundaries compared to subgrain rotation mechanism can be a consequence of high fluid content. Large-scale thrusting within the Brunovistulian basement is evidenced by the juxtaposition of calcitic and quartzitic mylonites with deformational microstructures reflecting pronounced contrasts of deformational styles. Fully plastic vs. fully brittle behaviour of quartz represents the most pronounced indicator of different deformational conditions between the lower unit of the Svratka Dome and the other domains of the Brunovistulian basement. In the lower tectonic unit of the Svratka Dome the microtructures of calcite mylonites indicate stresses which were about four times lower than in the other two parts of the Brunovistulicum. Despite the deformational contrasts, the values of illite crystallinity (IC) measured do not show any spatial gradient which could be linked with the distribution of the contrasting deformational microstructures. The paleothermometric data which are available to date suggest maximum paleotemperatures of 250-300 C for all three studied domains of Brunovistulian basement and it is suggested that the difference of Variscan peak temperatures between the three compared domains of the basement was not higher than several dozens of C. The observed deformational contrasts can thus be explained by an abrupt change of deformation mechanisms in both calcite and quartz at temperatures around 300 C.

Links

GA205/98/0751, research and development project

Name: Stratigrafický, faciální a tektonický výzkum vápenců při západním okraji brunovistulika

Investor: Czech Science Foundation, Stratigraphic, facial and tectonic research of localities of limestones of western Brunovistulian cover

MSM 143100004, plan (intention)

Name: Geologické procesy a jejich environmentální vyústění - styk variscid a alpid

Investor: Ministry of Education, Youth and Sports of the CR, Geological Processes and their Environmental Impact - Contact of the Variscides and Alpides

Citovat

ŠPAČEK, Petr, Jiří KALVODA, Eva FRANCŮ and Rostislav MELICHAR. Variation of deformation mechanisms within the progressive-retrogressive mylonitization cycle of limestones: Brunovistulian sedimentary cover (the Variscan orogeny of the Southeastern Bohemian Massif). Geologica Carpathica. Bratislava: Slovak Academic Press Ltd.,, 2001, vol. 52, No 5, p. 263-274. ISSN 1335-0552.

@article{386393,
   author = {Špaček, Petr and Kalvoda, Jiří and Franců, Eva and Melichar, Rostislav},
   article_location = {Bratislava},
   article_number = {5},
   keywords = {Brunovistulicum; microstructures; limestones},
   language = {eng},
   issn = {1335-0552},
   journal = {Geologica Carpathica},
   title = {Variation of deformation mechanisms within the progressive-retrogressive mylonitization cycle of limestones: Brunovistulian sedimentary cover (the Variscan orogeny of the Southeastern Bohemian Massif)},
   volume = {52},
   year = {2001}
}

TY  - JOUR
ID  - 386393
AU  - Špaček, Petr - Kalvoda, Jiří - Franců, Eva - Melichar, Rostislav
PY  - 2001
TI  - Variation of deformation mechanisms within the progressive-retrogressive mylonitization cycle of limestones: Brunovistulian sedimentary cover (the Variscan orogeny of the Southeastern Bohemian Massif)
JF  - Geologica Carpathica
VL  - 52
IS  - 5
SP  - 263
EP  - 263
PB  - Slovak Academic Press Ltd.,
SN  - 13350552
KW  - Brunovistulicum
KW  - microstructures
KW  - limestones
N2  - This study deals with the calcite mylonites of the Brunovistulian sedimentary cover developed in frontal thrust area of Moravian nappe units. The inhomogeneous structure of sedimentary protoliths allowed the analysis of the contrasting behavior of calcite in matrix and porphyroclasts and the interpretation of microfabric evolution during deformation under low temperature conditions. Several stages of microfabric evolution characterizing progressive as well as retrogressive deformation are distinguished. Generally, the progressive phase of mylonitization is characterized by grain growth in the matrix and the grain size reduction of the porphyroclasts leading to a stress-induced equilibration of grain size. During the initial deformational stages the calcitic porphyroclasts deformed brittlely and the strain was strongly localized into the ductile matrix. With continuing evolution the onset of the dynamic recrystallization of porphyroclasts occured, which obviously preceded a significant grain growth in the matrix. With rising temperature during deformation, grain growth predominated after grain size homogenization was finished. The lack of effective dynamic recovery along the stages of the progressive low temperature phase of deformation is discussed. Core-and-mantle structures which are characteristic for initial stages of progressive deformation carry microfabric features which document the dominance of grain boundary bulging and/or nucleation recrystallization. Formation of subgrains within the porphyroclasts is only a rarely observed feature which probably could not led to significant grain size reduction. The higher effectiveness of nucleation and recrystallization via migration of grain boundaries compared to subgrain rotation mechanism can be a consequence of high fluid content. Large-scale thrusting within the Brunovistulian basement is evidenced by the juxtaposition of calcitic and quartzitic mylonites with deformational microstructures reflecting pronounced contrasts of deformational styles. Fully plastic vs. fully brittle behaviour of quartz represents the most pronounced indicator of different deformational conditions between the lower unit of the Svratka Dome and the other domains of the Brunovistulian basement. In the lower tectonic unit of the Svratka Dome the microtructures of calcite mylonites indicate stresses which were about four times lower than in the other two parts of the Brunovistulicum. Despite the deformational contrasts, the values of illite crystallinity (IC) measured do not show any spatial gradient which could be linked with the distribution of the contrasting deformational microstructures. The paleothermometric data which are available to date suggest maximum paleotemperatures of 250-300 C for all three studied domains of Brunovistulian basement and it is suggested that the difference of Variscan peak temperatures between the three compared domains of the basement was not higher than several dozens of C. The observed deformational contrasts can thus be explained by an abrupt change of deformation mechanisms in both calcite and quartz at temperatures around 300 C.
ER  -

ŠPAČEK, Petr, Jiří KALVODA, Eva FRANCŮ and Rostislav MELICHAR. Variation of deformation mechanisms within the progressive-retrogressive mylonitization cycle of limestones: Brunovistulian sedimentary cover (the Variscan orogeny of the Southeastern Bohemian Massif). \textit{Geologica Carpathica}. Bratislava: Slovak Academic Press Ltd.,, 2001, vol.~52, No~5, p.~263-274. ISSN~1335-0552.

Detailed Information on Publication Record